The mammalian nervous system comprises a peripheral nervous system (PNS) and a central nervous system (CNS). CNS comprises brain and spinal cord, and is composed of two principal classes of cells: neurons and glial cells. The fundamental cell of the brain is the neuron. The glial cells fill the spaces between neurons, nourishing them and modulating their function. Certain glial cells, such as oligodendrocytes in the CNS, also provide a myelin sheath that surrounds neural processes. The myelin sheath enables rapid conduction along the neuron. Besides, radial glia contains a population of neural stem and precursor cells, so it can function as a supplier of newborn neurons and glia.
CNS disorders affect a wide range of the population with differing severity. These disorders can be caused by various factors such as trauma, infections, degeneration, structural defects, tumors, blood flow disruption, and autoimmune disorders. CNS disorders encompass numerous afflictions such as neurodegenerative diseases (e.g., Alzheimer's and Parkinson's), acute brain injury (e.g., stroke, head injury, cerebral palsy) and a large number of CNS dysfunctions (e.g., depression, epilepsy, and schizophrenia). The common signs and symptoms of these CNS disorders are physical and/or cognitive impairments and personality changes. Dementia, for example, is characterized by several cognitive impairments including significant memory deficit and can stand alone or be an underlying characteristic feature of a variety of diseases, including Alzheimer Disease, Parkinson Disease, Huntington's Disease, and Multiple Sclerosis. Some of these disorders and diseases relate to cerebral cortex or a surgical injury of cerebral cortex. Exemplary diseases of cerebral cortex include Alzheimer's disease, Parkinson's disease, Creutzfeldt-Jakob disease, Huntington's disease, progressive supranuclear palsy, and corticobasal degeneration.